The Research On Unit Seperation Characteristics And Simulation Analysis Of Three-field Demulsification And Dehydration Equipment For Wasted Oil

With the industy developing rapidly,enormous wasted oil has been generated,which brings out a new challenge to nature environment and resource safety,etc.However,it is difficult for the single technological means and device,in the present,to satisfy the requirements for the efficient demulsification and dehydration during wasted oil recycling.The three-field synergy demulsification and dehydration technology and device,which integrates three physical fields,namely,pulse electric,swirl centrifugal and vacuum temperature field,and is complementary advantages,can achieve the separation process that cannot be achievement easily by conventional methods.Hence,designing and developing the three-field synergy demulsification and dehydration device have great practical significance to reuse of waste resources,environment protection and energy conservation.This research are supported by the project of‘Efficient Demulsification Mechanism of Waste Oil and Experiment Based on Three-field Coupling' and ‘Efficient Demulsification Mechanism of Three-field Coupling and Experiment Oriented to Recycling of Industrial Waste Oil',funded by the Chongqing Natural Science Found and Nationalal Natural Science Found,respectively.Considering the three-field synergy demulsification and dehydration device,the droplets' tensile deformation model in wire-cylinder electric field,numerical analyzing models of coupling unit body and coupled field separation were established.The studies of the emulsified droplet's polarization characteristics in wire-cylinder electric field,separation characteristics of coupling unit body,two-field coupling separation characteristics,and three-field synergy separation characteristics,provide theoretical guidance for developing efficient and reliable wasted oil recycling device and its application.First of all,droplet,in the wire-cylinder electric field,dynamics theory was studied.For wire-cylinder electric field,considering the deforming droplets,the polarization model was established by using ellipsoidal coordinates.The distribution of electric field and polarizability inside the deformed droplet were calculated.According to polarized droplets' force balance under the wire-cylinder pulse electric field,the kinetic model of droplets' tensile deformation was established.The electrical stress and flow stress were derived by using EDH theory,and the values of droplets' tensile deformation were obtained.The experiment results showed that the model of droplet deforming dynamics could correctly predict the deformation of a droplet subjectec to pulsed electric field generated by wire-cylinder plants.Secondly,separation characteristic of the body of coupling unit was simulated by founding its numerical model.Considering the functional characteristics of coupling field,dehydration hydrocyclone,which has two cone sections and tangential inlets,was selected as the body of coupling unit.The high pulse electric field generated by body and swirl centrifugal field can combine effectively.According to the preset parameter,the numerical analysis model of unit body separation was established.By the model,the influence of structure parameters,such as the nominal diameter of unit body,and operating parameters,such as inlet flow rate,on oil-water separation efficiency was calculated and analyzed.It provides supports for the design and application of coupling unit body.The experiment of body unit's oil-water separation showed that the results of numerical analysis model were reliable.Thirdly,separation characteristic of the unit of coupling double fields was simulated by founding its numerical model.Aiming at emulsified oil droplet was affected by pulsed electric field force in two-field coupling unit,the matrix form of Maxwell tensor induced by electric field were derived.By using the N-S equations in hydromechanics,continuity equations,and electrical field governing equations,numerical modes of two-field separation was established.By the UDF which is the user define program function,the influence of main operation parameters,such as inlet velocity,pulse electric amplitude and frequency,on the distributions inside the coupling field and oil-water separation efficiency was analyzed.It provides selective basis for determining the application conditions of coupling unit's efficient demulsification and dehydration.Lastly,separation characteristic of the three-field synergy demulsification and dehydration device unit was simulated,and the calculating results were verified by the experiment.Based on synthetically analyzing the influence of vacuum temperature field unit actual conditions and droplets coalcensenced by electric field of coupling unit in the three-field synergy demulsification and dehydration device,controlling equations of on viscosity-temperature and dispersed phase partical radius were founded,and by numerical analysis model of coupling field separation and actual temperature range of vacuum temperature unit,the influence of main operation parameters on the velocity field distributions in the typical section of dehydration unit and oil-water separation efficiency was analyzed under the specific heating condition.It provided theoretical guidance for determining the optimum working conditions of the three-field synergy demulsification and dehydration device.By the three-field synergy demulsification and dehydration orthogonal experiment of five factors,four levels,effect on separation by four operating parameters were analysiced.The optimal operating parameters of the device were gained by single factor experiment.The results showed that the datas obtained by numerical analysis were reasonable and reliable.